While there are 342 species of shrimp, they fall into three basic groups: warm-water shrimp, freshwater shrimp and cold-water shrimp.

The most popular and plentiful warm-water shrimp are categorized by the color of their shell (not the meat) when raw: White, brown, pink and black tiger.

White and Tiger shrimp may be wild-caught or farm-raised; brown and pink are wild-caught.

Finding freshly caught shrimp is rare – they are typically flash-frozen on the boat and shipped right away, resulting in a very high-quality product.

Fresh caught shrimp (that have never been frozen) are only available seasonally and typically only found in coastal areas.

Buy frozen, in-the-shell shrimp for the best results, as "fresh" shrimp are almost always frozen at sea then thawed for sale. After a few days, the flavor and texture of thawed shrimp deteriorate.

Shrimp are sold by size, based on the number of shrimp in a pound - "16/20" on the label indicates 16 to 20 shrimp per pound - look for shrimp from fifteen to thirty per pound for the best flavor and ease in preparation.

Look for firm shrimp that fully fill their shell, are free of grit and without black spots or discoloration/yellowing.

Check the ingredients on pre-packaged frozen shrimp. Frozen shrimp are often treated or enhanced with additives such as sodium bisulfate, STP (sodium tripolyphosphate) or salt to prevent darkening (which occurs as the shrimp age) or to counter "drip loss," the industry term referring to the amount of water in the shrimp that is lost as it thaws. Treated shrimp have a strange translucency and an unpleasant texture, so look for the bags of frozen shrimp that list "shrimp" as the only ingredient.

Some information adapted from the following sources: On Food and Cooking, The Science and Lore of the Kitchen by Harold McGee, Food Lover’s Companion by Sharon Tyler Herbst and Wikipedia.com.